24 January 2009

Biosequestration involves offsetting greenhouse gases by capturing and storing carbon
in soil and plants. This includes restoring soil carbon through better land management;
revegetation and reforestation; and biochar (converting biomass into charcoal, which
can be fixed in soil).

Land Management

According to the Garnaut Review, 70% of Australia is arid and semi-arid rangeland
degraded by marginal grazing. Garnaut estimates approximately 50% of Australia’s
2006 CO2e emissions (approximately 576 million tonnes, or Mt) could be absorbed
each year for the next 20-50 years by improved practices on Australian cropping
and grazing lands, and by revegetation1.

According to scientist Dr Christine Jones an increase of 0.5% in soil carbon on
2% of Australia’s agricultural land would absorb a volume of CO2e exceeding Australia’s
2005 emissions2.

CSIRO scientist Dr Phil Polglase estimates plantings to abate carbon emissions
are profitable over 9.1M hectares of economically marginal low rainfall land at
a carbon price of $20/tonne. Such plantings have potential to remove 143 Mt of CO2e
each year – equal to approximately 25% of Australia’s 2006 emissions3.

Forestry and revegetation are already partly recognized as carbon offsets under
Kyoto.

Biochar

Created by heating biomass in the absence of oxygen - a process called pyrolysis.
Half the carbon is turned into biochar (charcoal) and fixed in soil. The other half
is transformed into biofuels used to generate green energy.

Advocates such as 2007 Australian of the Year Tim Flannery contend its widespread
adoption could, over 20 years, remove the 200-250 Gt of carbon added to the atmosphere
since 18504.

Resources firm Alumina estimates its existing pilot project5 can scale
to offset 6 Mt of CO2e yearly. Alumina estimates total biochar potential of WA’s
wheat belt at 25 Mt yearly, and total national potential at 100 Mt yearly – equal
to approximately 17% of 2006 emissions.